Patent GB-768164-A (GB)
Title: Improvements in or relating to blasting device
Inventor: JR EDWARD C FILSTRUP
IPC: F42B3/06
Filed: 1954-10-19
Abstract: 768,164. Fluid-pressure blasting devices. OLIN MATHIESON CHEMICAL CORPORATION. Oct. 19, 1954, No. 30045/54. Class 9 (1). A fluid-pressure cartridge 10 connected by a conduit 12 to a source of gas has a neck 14 of reduced diameter with a screwthreaded part 16 separated .by a peripheral groove 18 from the neck opening. A sleeve 20 screwed on to the neck 14 extends beyond the neck to receive a clamping ring 30 of stepped external diameter, the ring ibeing of such length that when it bears against the neck 14 its outer end is aligned with diametrically opposed slots 24 in the sleeve. A venting cap 40, provided with discharge ports 46, is screwed into the sleeve 20 to hold a plate 50 against the ring 30. Plate 50, which is preferably rectangular,is of such a size that it seals the venting cap from the container 10 and has a slight clearance with the end walls of the slots 24, at the same time being sufficiently long to project beyond the sleeve, so that it :can 'be easily gripped through the slots..Annular rings 52, 54 seated in grooves in the container 10 and the ring 30 seal the joint [between the ring and the container and further sealing means are provided between the sleeve and the container. A conduit 13 may be connected to the conduit 12 2 so that incoming air iis :discharged near the plate 50 to cool the neighbourhood of the plate. The conduit mayhave perforations along ;its length for a similar purpose. When compressed air or gas is fed into the container 10, the pressure inside :rises until finally the plate :50, 'which may be of ;mild steel, rupturesalong the rim of the ring 30 venting the stored gas through the ports 46. Thesevered part of the plate :is carried by the gases to the end wall of the cap 40. To reset the device, the cap 40 is rotated until the remainder of [the plate 50 can bewithdrawn through aslot 24. A new plate is then inserted andthe cap rotated toclamp the plate in position. Modifications in the shape of thesleeve 20 and clamping ring 30 are shown and described. Figs. 5 and 6 show a modification  in which the ring 60 has a peripheral groove 62 to receive a sealing ringand an annular groove 66 in the end face which abuts the plate 50. The groove 66 communicates through passages 68 with the interior of ring and seated in the groove is a sealing ring 70. instead of the rearwardlydirected ports of Fig. 1, large apertures 72 are provided in the venting cap40, Fig. 5, the bounding walls of the apertures being inclined rearwardly. In addition to two diametrically opposed apertures 72, smaller ports similar to ports 46 in Fig. 1, may be formed in the cap 40. The inner end wall 42 is preferably made conical to exert a folding action on the slug formed by shearing of the plate 50. In Fig. 9, the clamping ring is omitted and the neck 14 is elongated to provide a portion 80 abutting the plate 50. Vent passages 84 opening within the part 80 communicate with a groove 82 in the end face which receives a sealing member 86. The ports 92 in the venting cap are so shaped and placed that the slug from the ruptured plate is carried out of the cap 40 by the gases.